Twin-screw and triple-screw extrusion is an important method in the processing of polymeric materials and, relative to single-screw extrusion, has better mixing, reacting and degassing effects, suitable for processing plastics with poor thermal stability, especially suitable for processing blends. The plasticizing and conveying process of the twin-screw and triple-screw extrusion materials mainly depends on the shear drag of the screw in rotation, and therefore at present the twin-screw and triple-screw processed polymer materials have ubiquitously a long thermo-mechanical course, high processing energy consumption, poor mixing effects, large device structure, strong dependence on materials and other defects. In order to improve the mixing effects of the polymer materials and reduce the energy consumption of the polymer materials during the plasticizing and conveying, some researchers add kneading elements in some parts of the screw so that the local flow field in the plasticizing process is controlled by the elongational rheology. However, the control of this local flow field does not change the mechanism of the materials dominated by the shear rheology in the twin-screw and triple-screw extrusion plasticizing and conveying process.
With continuous emergence of the current new polymer materials such as plant fiber reinforced materials, biodegradable materials, and high performance materials, the requirements for dimensional accuracy, mixed dispersion characteristics, mechanical properties and other indicators of the polymer materials are also getting higher and higher at the same time, and therefore higher requirements are also put forward for the plasticizing device of the polymer materials. The vane plasticizing and conveying method is based on elongational rheology forces the materials to melt, plasticize and mix through the periodic change in the processing volume of the materials, wherein flow and deformation of the materials are mainly controlled by the tensile stress, and the principal velocity gradient is in the same direction as its main flow and deformation, which exhibits the elongational rheological behavior, thus solving the problem that the screw processing machinery plasticizing capacity mainly depends on the external and internal frictions of the materials. Compared with the screw plasticizing and conveying method, the vane plasticizing and conveying method has such advantages as low energy consumption, a short thermo-mechanical course, high adaptability to materials, and good dispersing and mixing effects. However, in the vane plasticizing and conveying process, the polymer conveying channel is non-streamlined, not conducive to plasticization and mixed modification of the processed thermosensitive polymer.
For current problems that all polymer material processing industries faced, it is of great significance for the polymer material processing field to develop a new plasticizing and conveying method and device that can significantly improve the mixed dispersion and plasticizing and mixing effects of the polymer materials, shorten the thermo-mechanical course and reduce the energy consumption, and effectively avoid the thermal degradation of the polymer materials in the processing process.